Glaciers, flows, and fans: Origins of a Neoproterozoic diamictite in the Saratoga Hills, Death Valley, California

Abstract

The Kingston Peak Formation of Death Valley, California, provides an exceptional archive of Cryogenian glaciation and concomitant rifting of Rodinia. In the Saratoga Hills, an 800 m thick succession of diamictite-dominated strata is exposed, allowing lithofacies and clast compositions to be studied in detail, and for the relative influence of glacial versus slope processes on sedimentation to be critically assessed for the first time. Two detailed sections, 400 m apart, allow four facies associations to be established: (1) Thinly Laminated Argillaceous Sandstone (interpreted as low density turbidites), (2) Laminated, Deformed, and Brecciated Limestone (interpreted as carbonate-sourced turbidites), (3) Bedded Massive Diamictite (interpreted as glacially-fed debrite), and (4) Interbedded Mudstone, Sandstone, and Diamictite (interpreted as stratified diamictite deposited via ice rafted debris and passing gradually into turbidites separated by intensely deformed intervals). Bedded massive diamictite is dominant in the succession and shows a gradual up section transition into interbedded mudstone, sandstone, and diamictite. This succession is interpreted to record a waning glacial influence: from glacially sourced debris flows to stratified diamictite strongly influenced by ice rafted debris. Clasts in the diamictite include carbonate, siliciclastic intraclasts, granite, diabase, gneiss, and quartzite. Clast presence profiles suggest that in spite of the comparable along-strike facies profiles between the two logs, clast content is significantly different within the same stratigraphic unit. This finding suggests that clast content is of little use in aiding correlation and lithostratigraphic subdivision of the Kingston Peak Formation. The differences in clast compositions is envisaged to be due to complex drainage network. Examinations of the sedimentary structures and stacking pattern of the lithofacies, complex drainage network, and localized deformation features of FA4 all support deposition as part of a trough mouth fan system.